Proximity faucet power source detection

ABSTRACT

A fluid dispensing device and method for controlling the device are provided. The device includes a housing defining a fluid outlet. A valve controls the flow of fluid to the outlet. A sensor is configured to detect an object outside of and proximate to the housing. A solenoid is configured to move the valve between an open position and a closed position. A controller is configured to receive the output signal of the sensor, determine a characteristic of noise in the output signal such as a level of noise; adjust at least one of a sampling rate of the output signal and an amount of filtering of the output signal responsive to the characteristic of noise in the output signal, and transmit a control signal to the solenoid responsive to the output signal.

BACKGROUND a. Field

This disclosure relates generally to fluid dispensing devices used tocontrol the flow of fluid and methods for controlling such devices. Morespecifically, this disclosure pertains to automated fluid dispensingdevices in which variation in noise levels in a signal from a proximityor similar sensor is detected and used to identify the source of thenoise and the resulting actions taken to improve sensor reliability.

b. Background Art

Automated faucets (also referred to as hands-free or touchless faucets)and other fluid dispensing devices employ a sensor to identify whetheror not a person or other object is present. The sensor generates asignal that is used by a control circuit to turn the faucet on or off.The signal, however, is subject to induced noise from electromagneticfields generated by electrical devices in the surrounding environment.The noise may be transmitted to the sensor by conductive emissions from,for example, alternating current power connections, batteries, or groundconnections and by radiated emissions from nearby conductive objects(e.g., a sink, hoses, or a drain). It is possible to reduce the level ofnoise in a signal by filtering the signal. Different devices in thesurrounding environment for a faucet may generate different levels ofsignal noise, however, and applying a filter that is sufficient toreduce noise in environments with a low signal to noise ratio willconsume significant power even in environments with a high signal tonoise ratio.

The inventors herein have recognized a need for a faucet that willovercome one or more of the above-identified deficiencies.

BRIEF SUMMARY

A fluid dispensing device for controlling the flow of fluids and amethod for controlling a fluid dispensing device are provided. Inparticular, a fluid dispensing device and method are provided thatdetermine the level of noise in a signal from a proximity or similarsensor associated with the device and, in response, determines the typeof actions taken to improve sensor reliability.

A fluid dispensing device in accordance with one embodiment includes ahousing defining a fluid outlet. A valve controls the flow of fluid tothe fluid outlet. The device further includes a sensor configured todetect an object outside of and proximate to the housing. The devicefurther includes a solenoid configured to move the valve between an openposition and a closed position. The device further includes acontroller. The controller is configured to receive the output signal ofthe sensor and to perform a process for addressing noise in the outputsignal. The process includes determining a characteristic of noise inthe output signal and adjusting at least one of a sampling rate of theoutput signal and an amount of filtering of the output signal responsiveto the characteristic of noise in the output signal. The controller isfurther configured to transmit a control signal to the solenoidresponsive to the output signal.

A fluid dispensing device in accordance with another embodiment includesa housing defining a fluid outlet. A valve controls the flow of fluid tothe fluid outlet. The device further includes a sensor configured todetect an object outside of and proximate to the housing. The devicefurther includes a solenoid configured to move the valve between an openposition and a closed position. The device further includes a sensorsubcontroller. The sensor subcontroller is configured to receive theoutput signal of the sensor and determine a characteristic of noise inthe output signal. The sensor subcontroller is further configured toadjust at least one of a sampling rate of the output signal and anamount of filtering of the output signal responsive to thecharacteristic of noise in the output signal. The device furtherincludes a solenoid subcontroller configured to transmit a controlsignal to the solenoid responsive to the output signal.

A method for controlling a fluid dispensing device in accordance withone embodiment includes the step of receiving an output signal of asensor configured to detect an object outside of and proximate to ahousing of the fluid dispensing device. The method further includes thesteps of determining a characteristic of noise in the output signal andadjusting at least one of a sampling rate of the output signal and anamount of filtering of the output signal responsive to thecharacteristic of noise in the output signal. The method furtherincludes the step of transmitting, responsive to the output signal, acontrol signal to a solenoid configured to move a valve between an openposition and a closed position to control the flow of fluid to a fluidoutlet defined in the housing.

The foregoing and other aspects, features, details, utilities, andadvantages of the disclosed embodiments will be apparent from readingthe following description and claims, and from reviewing theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of one embodiment of a fluid dispensingdevice.

FIGS. 2A-2D are flowcharts illustrating embodiments of a method forcontrolling a fluid dispensing device.

DETAILED DESCRIPTION

Referring now to the drawings wherein like reference numerals are usedto identify identical components in the various views, FIG. 1illustrates one embodiment of a fluid dispensing device 10 for use incontrolling the flow of fluid from a fluid source. In the illustratedembodiment, device 10 comprises a faucet that is used to control theflow of water from municipal or home water lines and is adapted for usein a kitchen or bathroom sink. It should be understood, however, thatthe teachings herein could be implemented in a variety of devicesincluding those used in showers and bath tubs and on toilets. Device 10may include a housing 12, fluid conduits 14, 16, 18, 20, a mixer 22 anda fluid control system 24.

Housing 12 is provided to direct fluids to a precise location and toprovide an aesthetically pleasing appearance to a user. In theillustrated embodiment, mixer 22 and actuator 24 are disposed outside ofhousing 12. It should be understood, however, that one or more of mixer22 and system 24 (or components thereof) could alternatively be disposedwithin housing 12 in which case housing 12 would also provide protectionfor these components from foreign objects and elements and position andorient the components relative to one another. The exterior of housing12 may assume a variety of forms determined by both functional andaesthetic configurations. In the illustrated embodiment, housing 12defines an inlet 26 configured to receive fluid from conduit 20. Inlet26 may be formed at one end of housing 12 and may include featuresformed therein for retaining conduit 20 or for supporting couplingelements used to retain conduit 20. Housing 12 may also define an outlet28 at an opposite end of housing 12 through which fluid exits device 10for use by a user of device 10. Housing 12 may consist of a single,unitary member or multiple members joined to one another in a variety ofways to form a fluid tight seals including through use of adhesives,welds, or fasteners with a seal formed around between or around theintersection of the members. A mounting stud 30 may be provided tosecure device 10 to surrounding structure and may extend from housing12. The stud 30 may, for example, be threaded and may be inserted in anaperture on one side of a deck/counter 32 surrounding a sink and securedusing a nut 34 placed over the stud 30 and rotated until the nut 34abuts the underside of the deck/counter 32. Isolators 35 made fromelectrically insulative materials may be disposed above and belowdeck/counter 32 to isolate housing 12 and stud 30 from deck/counter 32and ground.

Fluid conduits 14, 16 are provided for delivering hot and cold fluids tomixer 22. It should be understood that “hot” and “cold” as used hereinrefer to a difference in relative temperature among the fluids deliveredby conduits 14, 16 as opposed to any specific temperature values forthose fluids. In particular, the fluid conveyed by hot fluid conduit 14will have a higher temperature than the fluid conveyed by cold fluidconduit 16 and will typically be heated by a conventional water heateror similar device. Conduits 18, 20 are provided to deliver fluid frommixer 22 to inlet 26 of housing 12. Conduits 14, 16, 18, 20 may be madefrom conventional metals and/or plastics and typically comprise amulti-layer wall having metallic and/or thermoplastic layers configuredto achieve a variety of desirable characteristics including, forexample, fluid sealing, temperature resistance and flexibility. Conduits14, 16, 18, 20 may be joined to housing 12, mixer 22 and/or othercomponents of device 10 using conventional coupling mechanisms.

Mixer 22 is provided control the ratio of hot and cold fluids that areultimately delivered to outlet 28. Mixer 22 is configured to receive afirst fluid from hot fluid conduit 14 and a second fluid from cold fluidconduit 16 and to output either the first fluid, the second fluid or amixture of the first and second fluids to conduit 18. Mixer 22 includesa valve 36 and an actuator 38 configured to allow a user to adjust theposition of valve 36 and thereby control the amount of fluids from eachof hot and cold fluid conduits 14, 16 that are output by mixer 22. Theactuator 38 may comprise a handle that is connected to the valve 36 by afastener and configured to rotate about an axis. Rotation of the handleadjusts the position of the valve 36. The actuator 38 is capable ofmoving the valve 36 to any of a plurality of positions with eachposition establishing a different ratio of the amount of fluid from thehot fluid conduit 14 relative to the amount of fluid from the cold fluidconduit 16 that is output by the mixer 22 to conduit 18. Although mixer22 is located below deck 32 and separate from housing 12 in theillustrated embodiment, it should be understood that mixer 22 could bedisposed within housing 12 and may be located above or below deck 32 invarious embodiments.

System 24 is provided to turn the device on or off in the presence of auser. System 24 may include a power source 40, a sensor 42, a solenoid44, a valve 46, and a controller 48 (which is subdivided in theillustrated embodiment into subcontrollers 48 ₁ and 48 ₂). Again,although system 24 is located below deck 32 and separate from housing 12in the illustrated embodiment, it should be understood that one or morecomponents of system 24 could be disposed within housing 12 and may belocated above or below deck 32 in various embodiments.

Power source 40 provides current to electronic components such as sensor42, solenoid 44 and controller 48. Power source 40 may comprise abattery or a capacitor and may be connected to external devices used forenergy harvesting. Power source 40 may also comprise an interface to theelectrical grid such as a building electrical outlet. In accordance withone aspect of the present disclosure, controller 48 may be configured toidentify the type of power source used based on a characteristic (e.g. alevel) of noise in signals measured by sensor 42.

Sensor 42 detects the presence of an object (e.g., a person) within adefined area outside of and proximate to housing 12. In the illustratedembodiment, sensor 42 is disposed below counter/deck 32 and may comprisea proximity/capacitance sensor that is in contact with stud 30 to form acapacitance circuit with housing 12 and stud 30. In other embodiments,sensor 42 may be disposed within housing 12. In other embodiments,sensor 42 may comprise a voltage sensor. The signal output by sensor 42is subject to varying levels of interference or induced noise resultingfrom electromagnetic fields generated in the environment surroundingdevice 10 by, e.g., power source 40, other electronic devices, andconductors (e.g. sinks, hoses or drains).

Solenoid 44 is provided to control the position of valve 46. In thepresence of an object, sensor 42 generates a signal and provides thatsignal to controller 48. In response, controller 48 outputs a signalthat causes solenoid 44 to open valve 46 and allow fluid flow throughvalve 46 from conduit 18 to conduit 20 (and ultimately to outlet 28 inhousing 12). When the object moves a sufficient distance away fromsensor 42, a signal from sensor 42 is sent and, in response, controller48 directs solenoid 44 to close valve 46 and prevent further fluid flowthrough valve 46. It should be understood that variations in the controlmethod disclosed herein are possible including methods in whichcontroller 48 directs solenoid 44 to maintain valve 46 in an openposition for a predetermined period of time before closing valve 46.

Valve 46 controls the flow of fluid from mixer 22 towards outlet 28.Valve 46 is capable of assuming an open position wherein fluid flowsfrom mixer 22 towards outlet 28 and a closed position blocking fluidflow from mixer 22 to outlet 28. Valve 46 is moved between the open andclosed positions responsive to the movement of solenoid 44.

Controller 48 is configured to control solenoid 44 responsive to thesignal generated by sensor 42. In the illustrated embodiment, thefunctionality of controller 48 is subdivided into a sensor subcontroller48 ₁ and a solenoid subcontroller 48 ₂. Therefore, it should beunderstood that the term controller as used herein encompassessituations where the functionality of controller 48 as describedhereinbelow is combined in a single controller or is divided amongmultiple sub-controllers configured for communication with one another.In the embodiment illustrated in FIG. 1, for example, sensorsubcontroller 48 ₁ is integrated with sensor 42 and configured toprocess the signal generated by sensor 42 including varying the samplingrate of the signal and/or filtering the signal as described hereinbelowwhile another subcontroller 48 ₂ is configured to receive the processedsignal and generate control signals for solenoid 44 in response.Controller 48 may comprise a programmable microprocessor or anapplication specific integrated circuit (ASIC). Controller 48 mayinclude a central processing unit (CPU) and an input/output (I/O)interface through which controller 48 may receive of input signalsincluding signals generated by sensor 42 and generate output signalsincluding those used to control solenoid 44. The I/O interface mayfurther include a user interface through which an installer can inputinformation and commands to controller 48 and/or receive informationfrom controller 48. In some embodiments, the user interface may comprisea display such as a liquid crystal or light emitting diode segmentdisplay or video display and pushbuttons or other input devices thatpermit a user to enter information or commands (e.g., by selecting froma menu on the display) and control the display of information outputthrough the user interface. It should be understood, however, that avariety of user interfaces may be employed including touchscreendisplays.

Controller 48 may be configured (encoded) with programming instructionsfrom a computer program (i.e. software) to perform a method forcontrolling device 10. The method may be performed when power is firstapplied to device 10 upon start-up of the device 10 followinginstallation and/or periodically after start up. Referring now to FIG.2A, the method may begin with the step 50 of receiving an output signalof sensor 42. As noted above, sensor 42 is configured to detect a personor another object outside of and proximate to housing 12 of device 10and to generate an output signal in response. Controller 48 may increaseor decrease the sampling rate for the signal from sensor 42 at start upand/or periodically after start up to measure the noise level and decideon the logic to apply.

In some circumstances, it may be desirable to allow a user, such as aninstaller, to request actions intended to address noise in the outputsignal from sensor 42 regardless of the actual characteristics of thesignal and the surrounding environment. For example, an installer maywant to test how the sensor 42 will act under certain conditions.Alternatively, the installer may know that the sensor 42 will be drawingpower from a particular power source (e.g., an alternating currentsource) that will generate a certain level of noise in the output signalfrom sensor 42. In some embodiments, therefore, controller 48 may beconfigured to receive a command from the installer through the I/Ointerface and to take certain actions with respect to the output signalin response to the command that are intended to reduce noise in theoutput signal. In one embodiment, controller 48 may perform the steps52, 54 of determining whether a user command to take an action toaddress noise has been received through the I/O interface of controller48 and, if so, to perform the commanded action such as by increasing atleast one a sampling rate for the output signal and an amount offiltering of the output signal.

In the absence of a user command, controller 48 may be configured toperform several steps in a process for addressing noise in the outputsignal. The process may begin with the step 56 of determining acharacteristic of noise in the output signal such as a level of noise inthe output signal. By determining characteristics of noise in the outputsignal, controller 48 is capable of identifying the source of the noiseand/or applying appropriate measures to reduce the noise. Step 56 mayinclude several substeps. In substep 58, controller 48 (or subcontroller48 ₁ in the illustrated embodiment) may be configured to apply a highpass filter to the output signal. In one embodiment, the high passfilter may be implemented by applying a low pass filter to the outputsignal to identify and extract the low frequency components of thesignal and then subtracting those components from the output signal. Thehigh pass filter is intended to attenuate those portions of the signalthat may be impacted by nearby personnel such as an installer of thedevice 10 so that the presence of an individual is not interpreted asfixed site noise that would otherwise impact the identification of thesource of noise and subsequent actions to address the source of thenoise. In accordance with one embodiment, step 56 may further includethe substep 60 of calculating a root mean square value of the remainingportions of the output signal. In accordance with another embodiment,step 56 may alternatively include the substeps 62, 64 of applying atransform (e.g., a Fourier transform) to the remaining portions of theoutput signal to obtain a frequency domain signal and perform anumerical analysis of the frequency domain signal. For example, in oneembodiment, the method may include calculating a power spectral densityof the frequency domain signal. Although exemplary embodiments are shownin substeps 60 and 62, 64 it should be understood that other valuesindicative of characteristics of noise in the output signal couldalternatively be calculated in either the time or frequency domains. Thevalues obtained in substeps 60, 64 may be compared against empiricallyderived values to identify the source of the noise. In particular,certain sources of induced noise will generate more noise than others.If the power source 40 for device 10 comprises an alternating currentpower source such as a connection to an electrical grid, the level ofnoise in the signal may be relatively high. If the power source 40comprises a battery, the level of noise in the signal may be relativelylow. Therefore, in devices that can draw on multiple power sources(e.g., where the primary power source is an alternating current sourcewith a battery for backup) or in devices that may be used with a varietyof power sources, the comparison can be used to identify the powersource 40 that is being used so that appropriate noise reductionmeasures are taken based on the likely level of induced noise goingforward.

Referring now to FIG. 2B, the method may continue with one or more stepsintended to mitigate or reduce the level of noise in the signal in orderto insure greater reliability in the output signal generated by sensor42. In accordance with one embodiment, the method may include the step66 of adjusting at least one of a sampling rate of the output signalfrom sensor 42 and an amount of filtering of the output signalresponsive to the characteristic of noise in the output signal. Step 66may include several substeps. In substep 68, controller 48 is configuredto compare a level of noise in the output signal to a predeterminedthreshold level. As noted above, root mean square or power spectraldensity values for varying levels of induced noise in the signal causedby conducted and radiated emissions from various devices can beempirically determined. From these values, one or more threshold valuescan be identified indicative of certain levels of noise at which it isdesired to perform some action. Depending on the results of thecomparison between the noise level indicated by the measured root meansquare value or power spectral density value obtained in step 56 and thepredetermined threshold level, various actions can be taken. In oneembodiment, controller 48 is configured to perform one of the substeps70 or 72 of increasing, or decreasing, the sampling rate of the outputsignal if the level of noise in the output signal meets a predeterminedcondition relative to the predetermined threshold noise level. Forexample, if the comparison in substep 68 indicates that the level ofnoise exceeds a predetermined threshold level, controller 48 (orsubcontroller 48 ₁ in the illustrated embodiment) may increase thesampling rate of the output signal to decrease the user detectionresponse time—the time between when an object is presented near device10 and water begins to flow out of outlet 28—and also increase thereliability of the information provided by the signal. Doing so willincrease the use of computational resources and power consumption frompower source 40, but will reduce or prevent false readings based onnoise in the output signal. If the comparison in substep 68 indicatesthat the level of noise does not exceed the predetermined thresholdlevel, controller 48 (or subcontroller 48 ₁ in the illustratedembodiment) may decrease the sampling rate of the output signal toincrease the user detection response time because doing so will decreasethe use of computational resources and power consumption from powersource 40 without sacrificing reliability. In devices employingbatteries as power source 40, this action can extend the life of thebattery. In another embodiment, controller 48 (or subcontroller 48 ₁ inthe illustrated embodiment) may be configured—either as an alternativeto increasing the sampling rate or, as shown in FIG. 2, in addition toincreasing the sampling rate—to perform the substep 74 of applying afilter to the output signal if the level of noise in the output signalmeets a predetermined condition relative to the predetermined thresholdnoise level (e.g., exceeds the predetermined threshold noise level). Theuse of additional filtering on the output signal will again increase theuse of computational resources and power consumption from power source40, but will reduce or prevent false readings based on noise in theoutput signal. Although the illustrated embodiment shows that a filteris applied if the level of noise meets a predetermined condition and thefilter is not applied if the noise does not meet the predeterminedcondition, it should be understood that variations are possibleincluding embodiments in which a greater degree of filtering is appliedwhen the condition is met and a lesser degree of filtering is appliedwhen the condition is not met and embodiments in which the noise levelis compared against multiple threshold levels with different degrees offiltering depending on whether the noise level meets predeterminedconditions relative to each threshold (e.g., if the detected noise levelis greater than a first noise level, apply one level of filtering, ifthe detected noise level is greater than a second noise level greaterthan the first noise level, apply a second level of filtering greaterthan the first level of filtering, etc.). For the benefit of aninstaller or other user, controller 48 may be configured to generateoutput signals indicative of various values including the output signal,the noise in the signal, and the impact of the filtering or other noisereducing measures on the signal. In one embodiment, controller 48displays data to a user through the user interface of the I/O interfaceincluding the mean signal level of the output signal, the root meansquare noise level determined in step 60 and the impact of applying afilter to the signal in step 74.

The method may include additional steps intended to mitigate or reducethe level of noise in the signal. For example, controller 48 may beconfigured in step 76 to adjust a sensitivity to sensor 42 responsive tothe level of noise or other characteristic of noise in the outputsignal. If the level of noise in the signal meets a predeterminedcondition relative to a predetermined threshold level of noise,controller 48 may adjust the sensitivity of sensor 42. For example, ifthe level of noise in the signal is relatively high, controller 48 maybe configured to increase the likelihood that a signal from sensor 42will be read as detecting the presence of a person or other object. Ifthe level of noise in the signal is relatively low, controller 48 may beconfigured to decrease the likelihood that a signal from sensor 42 willbe read as detecting the presence of a person or other object.

The method may conclude with the step 78 of transmitting, responsive tothe output signal, a control signal to solenoid 44. Controller 48 (orsubcontroller 48 ₂ in the illustrated embodiment) is configured togenerate control signals used to control the operation of solenoid 44and, as a result, the position of valve 46. In response to the outputsignal of sensor 42, controller 48 will transmit control signals tosolenoid 44. As discussed above, the responsiveness of controller 48 tothe output signal may be adjusted based on the level of noise detectedin the output signal.

Steps 56 (FIG. 2A) and 66 (FIG. 2B) described above are preferablyperformed using a relatively high amount of data taken over a relativelyshort timeframe (e.g., five hundred (500) data points at 200 Hz). Oncethe baseline noise level has been determined and remedial actions taken,however, it may be desirable to monitor for subsequent changes in thelevel of noise in the signal using less data in order to reduce powerconsumption within system 24. Therefore, controller 48 may perform anumber of steps to monitor for conditions in which the baseline noiselevel is unlikely to change (e.g., when a user of the fluid dispensingdevice is not present and no fluid is dispensed) and to determinewhether and when steps 56, 66 should be repeated. Referring now to FIG.2C, controller 48 may determine in step 80 whether water is beingdispensed based on the position of valve 46. If valve 46 is closed,controller 48 increments a timer in step 82 and determines in step 84whether the time has reached a predetermined level (e.g., correspondingto a set time such as two minutes). Steps 80, 82, 84 are repeated untilvalve 46 moves to an open position or the timer reaches thepredetermined level. Once the timer reaches a predetermined level,controller 48 again determines a characteristic of noise in the outputsignal from sensor 42. As compared to step 56 described hereinabove,however, controller 48 makes the determination using a relatively lowamount of data taken over a longer timeframe (e.g., sixteen (16) datapoints at 8 Hz). In one embodiment, controller 48 calculates, in step86, a room mean square value for the output signal and compares thevalue to a threshold value in step 88. It should be understood, however,that controller 48 could determine other characteristics of noise in theoutput signal including by performing steps similar to steps 62, 64(FIG. 2A) and 68 (FIG. 2B) described above. If the value meets apredetermined condition relative to the threshold value (e.g., exceedsthe threshold value) indicative of potential noise in the signal,controller 48 may determine in step 90 whether remedial actions, such asapplication of a filter, are already being applied to the output signal.If a filter is not being applied, controller 48 may return to step 56(FIG. 2A) to reevaluate potential noise in the signal using more data.If a filter is already being applied, controller 48 may return to step80. If the value determined in step 86 does not meet the predeterminedcondition relative to the threshold value (e.g., is less than thethreshold value), controller 48 may again determine in a step 92 whetherremedial actions, such as application of a filter, are already beingapplied to the output signal. If no filter is being applied, controller48 may simply return to step 80. If a filter is already being applied,the fact that the value determined in step 86 is below a threshold levelmay be indicative of a reduction in noise due to, for example, a switchfrom an alternating current power source to a battery (e.g., a backuppower source). In this circumstance, it may be desirable to disable thefiltering or other noise mitigating actions previously applied to theoutput signal in order to reduce power consumption. In steps 94 and 96,controller 48 may increment a counter and compare the counter to apredetermined value. The predetermined value is selected to delay achange in noise mitigation actions unless and until the reduced noiselevel has been maintained for a predetermined period of time. Therefore,if the counter does not meet a predetermined condition relative to thepredetermined value (e.g., is less than the predetermined value),controller 48 may return to the step 80. If the counter does meet thepredetermined condition (e.g., is equal to or greater than thepredetermined value), controller 48 may return to step 56 (FIG. 2A) toreevaluate the amount of noise in the output signal using more data.

If controller 48 determines in step 80 that valve 46 is open and thatwater is being dispensed from device 10, controller 48 may performadditional actions to reduce noise in the output signal as illustratedin FIG. 2D. It has been determined that the presence of a user of device10 and the output of water from device 10 can result in variation in theamount of noise in the output signal of sensor 42 and, in particular, anincrease in noise. Therefore, when water is output from device 10,controller 48 may perform the steps 98, 100 of further increasing thesampling rate of the output signal and applying an even greater level offiltering to the output signal. Controller 48 may determine in step 102whether valve 46 has closed and water is no longer being dispensed fromdevice 10 and may maintain the increased sampling frequency andadditional filtering until valve 46 is closed. Once valve 46 is closed,controller 48 may perform the steps 104, 106 of removing the additionalfiltering and decreasing the sampling rate of output signal. Thereafter,controller 48 may return to step 80 in FIG. 2C.

A fluid dispensing device and a method for controlling a fluiddispensing device in accordance with the present teachings isadvantageous relative to conventional devices and control methods. Inparticular, the device is configured to adjust to varying levels ofnoise that may be present in the output signal of a sensor 42 in orderto improve the reliability of the output signal when noise levels arerelatively high while conserving power when noise levels are relativelylow (e.g., to extend battery life in devices where power source 40comprises a battery).

While the invention has been shown and described with reference to oneor more particular embodiments thereof, it will be understood by thoseof skill in the art that various changes and modifications can be madewithout departing from the spirit and scope of the invention.

We claim:
 1. A fluid dispensing device, comprising: a housing defining afluid outlet; a valve controlling a flow of fluid to the fluid outlet; asensor configured to detect an object outside of and proximate to thehousing; a solenoid configured to move the valve between an openposition and a closed position; and, a controller configured to receivethe output signal of the sensor; perform a process for addressing noisein the output signal including determining a characteristic of noise inthe output signal; and, adjusting at least one of a sampling rate of theoutput signal and an amount of filtering of the output signal responsiveto the characteristic of noise in the output signal; and, transmit acontrol signal to the solenoid responsive to the output signal.
 2. Thefluid dispensing device of claim 1, wherein the controller is furtherconfigured, in determining the characteristic of noise in the outputsignal, to calculate a root mean square value of the output signal. 3.The fluid dispensing device of claim 2 wherein the controller is furtherconfigured, in determining the characteristic of noise in the outputsignal, to apply a high pass filter to the output signal prior tocalculating the root mean square value of the output signal.
 4. Thefluid dispensing device of claim 1, wherein the controller is furtherconfigured, in determining the characteristic of noise in the outputsignal, to: apply a transform to the output signal to obtain a frequencydomain signal; and, perform a numerical analysis of the frequency domainsignal.
 5. The fluid dispensing device of claim 4 wherein the numericalanalysis comprises a power spectral density of the frequency domainsignal.
 6. The fluid dispensing device of claim 4 wherein the controlleris further configured, in determining the characteristic of noise in theoutput signal, to apply a high pass filter to the output signal prior toapplying the transform to the output signal.
 7. The fluid dispensingdevice of claim 1 wherein the controller is configured, in adjusting theat least one of the sampling rate of the output signal and the amount offiltering of the output signal, to compare a level of noise in theoutput signal to a predetermined threshold noise level and to increasethe sampling rate of the output signal if the level of noise in theoutput signal meets a predetermined condition relative to thepredetermined threshold noise level.
 8. The fluid dispensing device ofclaim 1 wherein the controller is configured, in adjusting the at leastone of the sampling rate of the output signal and the amount offiltering of the output signal, to compare a level of noise in theoutput signal to a predetermined threshold noise level and to apply afilter to the output signal if the level of noise in the output signalmeets a predetermined condition relative to the predetermined thresholdnoise level.
 9. The fluid dispensing device of claim 1 wherein thecontroller is configured, in adjusting the at least one of the samplingrate of the output signal and the amount of filtering of the outputsignal, to compare a level of noise in the output signal to apredetermined threshold noise level and to decrease the sampling rate ofthe output signal if the level of noise in the output signal meets apredetermined condition relative to the predetermined threshold noiselevel.
 10. The fluid dispensing device of claim 1, wherein thecontroller is further configured to adjust a sensitivity to the sensorresponsive to the characteristic of noise in the output signal.
 11. Thefluid dispensing device of claim 1 wherein the sensor comprises acapacitance sensor and the housing forms part of a capacitive circuit.12. The fluid dispensing device of claim 1 wherein the controller isfurther configured to increase the at least one of the sampling rate ofthe output signal and the amount of filtering of the output signalresponsive to a user command received through an input/output interfaceof the controller.
 13. The fluid dispensing device of claim 1 whereinthe controller is further configured to: calculate a root mean squarevalue of the output signal when the valve has been in the closedposition for more than a predetermined period of time; compare the rootmean square value of the output signal to a threshold value; and, repeatthe process for addressing noise in the output signal when the root meansquare value of the output signal meets a predetermined conditionrelative to the threshold value and an amount of filtering being appliedto the output signal meets a predetermined condition.
 14. The fluiddispensing device of claim 1 wherein the controller is furtherconfigured to further increase the sampling rate of the output signaland the amount of filtering of the output signal when the valve is inthe open position.
 15. A fluid dispensing device, comprising: a housingdefining a fluid outlet; a valve controlling a flow of fluid to thefluid outlet; a sensor configured to detect an object outside of andproximate to the housing; a solenoid configured to move the valvebetween an open position and a closed position; a sensor subcontrollerconfigured to receive the output signal of the sensor; determine acharacteristic of noise in the output signal; and, adjust at least oneof a sampling rate of the output signal and an amount of filtering ofthe output signal responsive to the characteristic of noise in theoutput signal; and, a solenoid subcontroller configured to transmit acontrol signal to the solenoid responsive to the output signal.
 16. Amethod for controlling a fluid dispensing device, comprising the stepsof: receiving an output signal of a sensor configured to detect anobject outside of and proximate to a housing of the fluid dispensingdevice; determining a characteristic of noise in the output signal;adjusting at least one of a sampling rate of the output signal and anamount of filtering of the output signal responsive to thecharacteristic of noise in the output signal; and transmitting,responsive to the output signal, a control signal to a solenoidconfigured to move a valve between an open position and a closedposition to control the flow of fluid to a fluid outlet defined in thehousing.
 17. The method of claim 16 wherein the determining stepincludes the substep of calculating a root mean square value of theoutput signal.
 18. The method of claim 17 wherein the determining stepfurther includes the substep of applying a high pass filter to theoutput signal prior to calculating the root mean square value of theoutput signal.
 19. The method of claim 16, wherein the determining stepincludes the substeps: applying a transform of the output signal toobtain a frequency domain signal; and, calculating a power spectraldensity of the frequency domain signal.
 20. The method of claim 19wherein the determining step further includes the substep of applying ahigh pass filter to the output signal prior to applying the transform tothe output signal.
 21. The method of claim 16 wherein the adjusting stepincludes the substeps of: comparing a level of noise in the outputsignal to a predetermined threshold noise level; and increasing thesampling rate of the output signal if the level of noise in the outputsignal meets a predetermined condition relative to the predeterminedthreshold noise level.
 22. The method of claim 16 wherein the adjustingstep includes the substeps of: comparing a level of noise in the outputsignal to a predetermined threshold noise level; and applying a filterto the output signal if the level of noise in the output signal meets apredetermined condition relative to the predetermined threshold noiselevel.
 23. The method of claim 16 wherein the adjusting step includesthe substeps of: comparing a level of noise in the output signal to apredetermined threshold noise level; and decreasing the sampling rate ofthe output signal if the level of noise in the output signal meets apredetermined condition relative to the predetermined threshold noiselevel.
 24. The method of claim 16, further comprising the step ofincreasing the at least one of the sampling rate of the output signaland the amount of filtering of the output signal responsive to a usercommand.
 25. The method of claim 16, further comprising the steps of:calculating a root mean square value of the output signal when a valveof the fluid dispensing device has been in a closed position for morethan a predetermined period of time; comparing the root mean squarevalue of the output signal to a threshold value; and, repeating thedetermining and adjusting steps when the root mean square value of theoutput signal meets a predetermined condition relative to the thresholdvalue and an amount of filtering being applied to the output signalmeets a predetermined condition.
 26. The method of claim 16, furthercomprising the step of further increasing the sampling rate of theoutput signal and the amount of filtering of the output signal when avalve of the fluid dispensing device is in an open position.